Safe-Water Guidelines for Patients with Weakened Immunity

Your doctor or nurse will tell you if you should follow these guidelines.

When your immunity is weakened, it’s easier for you to get infections. It is very important to be careful about the water you use for drinking, cooking, and brushing your teeth. Following are some guidelines.

Tap water

Tap water is water from your faucet. It usually is considered safe if the water source is a city water supply or a municipal well that serves an area with a lot of people.

If you live in a small community, call your local water authority, and ask if your water is tested daily to detect “coliforms”.

Municipal water supplies are tested to make sure they have not become contaminated with bacteria which could come from animal feces or soil run off. If water tests show this type of a problem, a “boil water alert” may be reported. Drinking contaminated water could even cause healthy people to get sick.

Well water

If your water at home is from a private well or small community well, you should boil the water or use approved bottled water for drinking. Sometimes a well is more likely to become contaminated with bacteria. Bathing is not a problem using well water.

Water from a private well should be tested at least once each year. The water should be used only if the test shows that it is free from coliform organisms.

Your well is more at risk if:

• There is construction near it
• The well is shallow
• The well is near a dairy or livestock
• Flooding has occurred near the well

Test your water more often if it is at risk.

After spring runoff or any flooding, do not use well water until it has been tested.

No matter how often well water is tested, you can’t be sure it will stay safe. You have to test it again.

Boiling water to make it safe

To boil the water so it will be safe, heat it to a full rolling boil. Keep the rolling boil going for at least 1 minute before you use the water. Store the boiled water in a clean, covered container in the refrigerator. Throw out the water after 72 hours (3 days). Use this boiled water for

• Drinking
• Adding to frozen orange juice and frozen lemonade
• Making drinks from crystals or powders, like Kool Aid
• Making ice
• Cooking
• Basic mouth care, like brushing your teeth

Bottled water

Labels that say well water, spring water, Artesian well water, or mineral water do not guarantee that the water is safe for you to drink.

If you buy bottled water, be sure that the label has one of the following statements about how it was cleaned:

• Reverse osmosis filtration
  OR
• Distillation
  OR
• Filtered through an absolute 1 micron or smaller filter (NSF-standard #53 for cyst removal)

The International Bottled Water Association (IBWA) can tell you if your bottled water has undergone one of these safety processes. Call 1-800-928-3711 or visit the website at www.bottledwater.org.

Water filters

If you get water from a city water supply or a large municipal well, the water does not need to be filtered to be safe. If you have a home water filtration system, read the label to find out who makes it. Call that company and ask what you need to do to keep your filter clean. Explain your medical condition. If you aren’t sure your filter will make your water safe, it may be better to drink boiled water or approved bottled water.

Portable water filters such as Brita® or Pur®, as well as refrigerator-dispensed water and ice machine systems do not meet filtration standards. They remove chemical impurities but not bacteria.

Most water filtration systems can make the water safe only if chlorine has been added to the water supply. They will not make water safe if it is from a private well or small community well.  If your water comes from a private well or small community well, boil the water or use approved bottled water.

For more information on approved filtering systems, visit the National Sanitation Foundation’s Web site, or call 1-800-673-6275.

Reviewed February 2023